A storage domestic solar hot water system with a back layer of phase change material

► A solar collector and a storage tank are integrated with a back layer of paraffin wax. ► Plate temperature increased up to a distance of 2.5 m from entrance. ► Liquid PCM transferred heat to the circulating water at low off-sunshine hours. Phase Change Materials (PCMs) may be incorporated in solar thermal energy systems to act as latent heat storage media offering a high storage capacity compared to sensible heat storage. In this work, a storage solar collector that consists of six 80-mm diameter copper pipes connected in series is integrated with a back container of paraffin wax as a PCM thermal storage media. Outdoor experiments are carried out to demonstrate the potential of the storage solar system for water heating. The performance of the system is evaluated by calculating the various performance factors of the collector. The plate temperature is found to increase up to a distance of 2.5m from entrance, after which an almost steady temperature is noticed. Such trend was in contrast to the increasing trend previously noticed for a similar system without the PCM back layer. During off-sunshine hours, the liquid PCM transferred heat to the absorber, part of which was conducted as a useful heat in the circulating water. Therefore, the water continued to get heated after sunset, as the PCM acted as a heat source.